We occasionally have clients that purchase vehicles from out of state dealers. Sometimes the dealers will suggest that the client drive their new car home with temporary plates obtained in their state. The problem with this is that Massachusetts does not issue Temporary Plates to its residents per MGL Chapter 90, Section 9. So, if a Mass. resident were to purchase a car in NY and obtain temporary plates there and drive it into Massachusetts, they could be pulled over for operating an unregistered vehicle which would involve a fine and also a surcharge on your insurance.
The best thing is to register the car in Massachusetts, put the new Mass. plates on it and drive it home or have the vehicle delivered to you by the dealership and register it as soon as possible so that you can then drive it. In any case, always give your agent a call when you are buying a new car to discuss the registration options and insurance coverages.